Standard Roof Rafter Sizes

Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run.

Standard roof rafter sizes.

Typical rafter spacing codes will specify a minimum spacing of 16 inches 19 2 inches or 24 inches. If you re building rafters and aren t sure where to start when determining the length of your lumber you re in the right place our rafter stock size calculator shows you how long your rafters should be so you ll know what you need in terms of framing lumber dimensional lumber studs and more. There is no standard spacing it depends on what size of rafters you want to use and the span of your shed. For standard shed roof rafter spacing see rafter span chart.

For example you can span a 1 grade no knots southern yellow pine a greater distance than a 2 grade with knots southern yellow pine. Rafters must be strong enough to hold the roof sheathing and the shingles. For instance 2 grade 2x4s at 16 on center will span just over 9. This is the distance between trusses.

Builders aren t bound by standard rafter spacing measurements. Just enter the dimensions of the roof rise and run to get started. Automatically calculate suitable rafter sizes enter a specific rafter size 1 3 timber strength class c16 cost effective for most applications. The lengths and sizes of joists vary depending on the species and quality of the lumber used.

Imposed loads roof snow load and short term point load altitude not exceeding 100m. The steeper the roof the more expensive the trusses get because the longer the boards get and the more roof area increases. This sizing guide for roof rafters will help determine what you need for your small project. There are several variables to consider when determining the proper rafter size.

You will also incur additional costs because it is much harder to deck and shingle a roof that is 12 12 pitch versus a 4 12 roof. If your local building authority has a rafter spacing code you may not space rafters wider than required by code. If you get premium kiln dried lumber then you could span 10 5 with the same size of lumber and. 0 75 kn m snow load.

Roof pitch between 15 and 22 5 degrees with rafter spacing strength class c16 size of rafters in mm 400mm 450mm 600mm. Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch. Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter. The standard roof truss spacing is 2.